Herpes is the only disease which comes under this heading, so far as the horse is concerned. It consists of the eruption of vesicles in patches of an irregular form; the vesicles are sometimes very large, and are called blebs or bullae. The lips in the horse are sometimes the seat of the disease, and it also appears round the coronets; the mucous membrane of the mouth is also sometimes invaded. A characteristic variety of the disease is herpes circinatus, in which the eruption of vesicles appears on various parts of the body. In this form the disease is commonly described as ringworm; it is, however, quite distinct from the true contagious ringworm, which depends on the presence of a parasitic plant. In herpetic ringworm the vesicles appear in a ring surrounding a patch of healthy skin, whereas in parasitic ringworm the disease commences in the centre and spreads outwards. Herpes depends as a rule upon some derangement of the digestive organs, and ceases when the normal condition is restored. Very little treatment is necessary. The local irritation can be removed by the application of a lotion composed of a solution of the acetate of lead and glycerine, and any existing derangement of the system may be met by judicious dieting, and the administration of alterative medicine, as a mixture of equal parts of sulphur, nitrate of potash, and resin, which may be mixed with the food and given morning and evening.